49 lines
1.4 KiB
Factor
49 lines
1.4 KiB
Factor
! Copyright (c) 2009 Doug Coleman.
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! See http://factorcode.org/license.txt for BSD license.
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USING: io.encodings.ascii io.files kernel math
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project-euler.common roman sequences ;
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IN: project-euler.089
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! http://projecteuler.net/index.php?section=problems&id=089
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! DESCRIPTION
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! -----------
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! The rules for writing Roman numerals allow for many ways of writing
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! each number (see FAQ: Roman Numerals). However, there is always a
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! "best" way of writing a particular number.
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! For example, the following represent all of the legitimate ways of
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! writing the number sixteen:
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! IIIIIIIIIIIIIIII
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! VIIIIIIIIIII
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! VVIIIIII
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! XIIIIII
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! VVVI
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! XVI
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! The last example being considered the most efficient, as it uses
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! the least number of numerals.
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! The 11K text file, roman.txt (right click and 'Save Link/Target As...'),
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! contains one thousand numbers written in valid, but not necessarily
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! minimal, Roman numerals; that is, they are arranged in descending units
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! and obey the subtractive pair rule (see FAQ for the definitive rules
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! for this problem).
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! Find the number of characters saved by writing each of these in their minimal form.
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! SOLUTION
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! --------
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: euler089 ( -- n )
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"resource:extra/project-euler/089/roman.txt" ascii file-lines
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[ ] [ [ roman> >roman ] map ] bi
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[ [ length ] map-sum ] bi@ - ;
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! [ euler089 ] 100 ave-time
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! 14 ms ave run time - 0.27 SD (100 trials)
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SOLUTION: euler089
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